The reduced feature set in the web app is either development hasn't reached parity, or they want it to be just enough to compete with Google sheets but keep people using the windows app.

A better price of software would be several different tools. But Microsoft want to keep the features set and backwards compatibility and the users don't want big changes so the messy mishmash it what results.

Excel is used as a app builder, a database, plotting tool, table formatting, dashboard, visual basic environment, simulation environment there's probably many more uses. I think it was supposed to be a calculator and accountancy book combination.

If anyone knew excel (or spreadsheets in general) would become what they did they would design it completely differently. A database that links to different pieces of software would be much better. That can't exist now, because the markets consumed by excel.